New electrode materials derived from polyquinonic ionic compounds and their use in electrochemical generators

ABSTRACT

The present invention is concerned with novel compounds derived from polyquinonic ionic compounds and their use in electrochemical generators.

FIELD OF THE INVENTION

[0001] The present invention is concerned with novel polyquinonic ioniccompounds useful as electrode materials used for example inelectrochemical generators.

BACKGROUND OF THE INVENTION

[0002] Electrode materials derived from transition metals, in particulartransition metals binary chalcogenides, such as TiS₂, VO_(x) (2≦x≦2.5),ternary oxides such as LiNiO₂ LiCoO₂, Li_(1+x)Mn_(2−x)O₄(0≦x≦1), etLiV₃O₈, are known. These materials are however often relatively toxic.With the exception of vanadium derivatives, the capacities arepractically modest, i.e. on the order of 100 Ah.g⁻¹, and their potential(about 4 V vs Li⁺/Li^(o)) are beyond the domain of stability of solid orliquid electrolytes. They are therefore problematic in terms of safety.

[0003] Organic compounds like conjugated polymers work through aninsertion mechanism of anions taken from the electrolyte. The masscapacities resulting therefrom are consequently low and the cyclingpossibilities are disappointing.

[0004] Other known compounds are those of the polydisulfide type, which,even if they do not have intrinsic electronic conductivity, possessinteresting redox properties and mass capacities ((≧300 Ah.g⁻¹),particularly oxidizing coupling derivatives of2,5-dimercaptothiadiazole. However, the resulting reduction products andintermediates are lithium salts like conjugated thiolates with anitrogen atom. Delocalization of the charge on the polarisable anioniccenters like sulfur and nitrogen, lead to a relatively importantsolubility in the electrolytes, as well as a reduced cycling life span.

[0005] Monoquinones are organic compounds known for their redoxproperties, but the potentials are of little interest (on the order of2.2 V vs. Li⁺/Li^(o)), and the neutral oxidized compounds are soluble inthe electrolytes. Polymers bearing quinonic functions such as thoseresulting from hydroquinone and formaldehyde polycondensation, are notelectrochemically active because of the reduced mobility of the chargecarriers, ions and electrons, in the absence of highly polar proticsolvents like water.

SUMMARY OF THE INVENTION

[0006] The present invention concerns electroactive compounds derivedfrom anion salts bearing at least 2 quinone functions cumulated,conjugated, or both, in the same molecule. More specifically, theinvention comprises a redox compound having at least one state ofoxidation state represented by the general formula:

[0007] wherein

[0008] M⁺ represents an alkaline metallic cation, an alkaline-earthcation, a transition metal cation, a rare earth cation, anorganometallic cation, an organic cation of the “nium” type, arepetitive unit of a cationic oxidized conjugated polymer, or amonomeric or polymeric cation optionally having a redox character;

[0009] X is oxygen, NCN, or C(CN)₂;

[0010] Z is C—Y⁻ or N⁻;

[0011] Y represents oxygen, sulfur, NCN, —C(CN)₂, with the proviso thatwhen Y is sulfur and n is ≦4, then X is oxygen;

[0012] R₁ is absent, O, S, NH, —(C═C)_(r)—, —(W═W)_(r)— wherein W isindependently CR⁶ or N; r varies between 1 and 12; and R⁶ is H, halogen,CN, or C₁₋₁₂ alkyl, C₂₋₁₂ alkenyl or C₆₋₁₄ aryl optionally having one ormore substituents oxa, aza or thia; and wherein 2 R⁶ groups can bebonded to form a cycle comprising from 3 to 7 members;

[0013] R² and R³ are the same or different and are absent, a carbonateddivalent radical, optionally substituted with aza, oxa or thia;

[0014] q varies between 0 et p;

[0015] p varies between 1 and 5;

[0016] n varies between 1 and 10⁴; and

[0017] wherein two of R¹, R² and R³ can be bonded together to form acycle comprising 3 to 7 members.

[0018] For the purposes of the present invention, when n is 4 or less,the compound of the invention is not considered a polymer. In addition,the expression “divalent radical” is defined as an alkylene, an arylene,or an arylalkylene of from 2 to 200 carbon atoms, and optionallycomprising one or more substituents aza, oxa or thia.

[0019] The present application further concerns an electrode materialcharacterized in that it contains, in whole or in part, a compound ofthe invention, and an electrical energy storage system such as a primaryor secondary generator or a super capacity comprising an electrolyte, atleast one negative electrode and at least one positive electrodecomprising a compound of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In the present invention, a new family of electroactive compoundsderived from anion salts bearing a plurality of quinone functionscumulated and/or conjugated in the same molecule is described andclaimed. It has been found that such type of compounds have a highcapacity, i.e. equal or higher than 300 Ah.g⁻¹, obtained at potentialscomprised between 3.5 et 1 V vs. Li⁺/Li^(o), thus in the domain ofstability of conventional aprotic electrolytes, liquid or solid, andallowing the making of positive and negative electrodes for generators.Further, the corresponding salts do not, whatever their degree ofoxidation, solubilize significantly in liquid electrolytes or aproticpolymers. The kinetic of the redox reaction in solid phase is noticeableand comparable to that of inorganic insertion materials. It has alsobeen found that by replacing the oxygen atom of the neutral quinonicgroups CO with NCN groups or C(CN)₂, and/or the replacement of theoxygen atom of the quinonic groups negatively charged with anionicgroups N⁻, NCN⁻ or C(CN)₂ ⁻ had the same interesting properties in termsof the redox activity. The redox potential is displaced of about 300 mVtowards the positive values by replacing a neutral quinonic oxygen withan NCN or C(CN)₂. The chemical methods to perform these substitutions onthe quinonic groups are well known to anyone of ordinary skill in theart.

[0021] The redox compounds of the present invention include alsopolyquinones wherein the negatively charged oxygen of the quinonicgroups is replaced with sulfur S⁻. In this case, charge conjugation withan oxygenated group CO neutral and weakly polarisable and moreelectronegative, significantly lowers the solubility of thecorresponding ionic derivatives, in particular in electrolyticsolutions. An additional degree of oxidation is then obtained byoxidative duplication of CS⁻ groups to form disulfide bridges CS—SC.

[0022] These polyquinonic compounds can also be part of the polymersinto which the charges are conjugated along the polymeric chain. In sucha case, the solubility of these rigid macromolecules is null, whateverthe charge borne by the polymer, thus including the neutral state.

[0023] Because the compounds of the present invention are anion salts,i.e., negatively charged, it is necessary to combine them with a cationin order to have a global neutral charge. The preferred cations comprisethe proton, alkaline cations like Li, Na, K, Cs; alkaline-earth cationslike Mg, Ca, Ba; transition metal cations like Cu, Zn, Pb, Fe, Ni, Co,Mn, V, Cr; rare earth cations; organometallic cations likemetallocenium; cations of the <<ium>> type such as ammonium, amidinium,guanidinium, pyridinium, imidazolium, triazolium, imidazolinium,sulfonium, phosphonium, iodinium; a repetitive unit of an oxidizedcationic conjugated polymer such as polypyrrole, polythiophene,polyquinolines; cations in the form of monomers or polymers optionallyhaving a redox character such as viologenes of formula[—(R″NC₅H₄—C₅H₄N—)²⁺]_(n) wherein R″ comprises C₂₋₁₂ alkylene, C₆₋₁₄arylene or C₆₋₁₄ arylene C₂₋₁₂ alkylene, each optionally substitutedwith oxa, aza ou thia. The lithium cation and the proton areparticularly preferred. Other ions can be present in the electrolyticmedium and/or in the electrode material, and can contribute to improvethe conductivity of the interfacial properties. The potassium ion isadvantageously used in such instance, as well as cations derived fromquaternized imidazolium.

[0024] To the redox capacity of the molecules of the present inventioncan be added that of the cation when the latter possesses many degreesof oxidation. Cations of iron, copper or manganese, as well asmetallocenes, are particularly interesting for such application. Organiccations with redox properties, such as viologenes, are similarly useful.These cations can optionally be part of a polymeric chain.

[0025] The compounds of the present invention possess high specificcapacities of redox exchange, and in fact superior to those ofconventional inorganic compounds. The great variety of functional groupsavailable allows choosing redox potentials in a wide range ofpotentials, typically between 0.1 to 3.7 V vs. Li⁺/Li^(o). Compoundswith redox couples comprised between 0.1 and 2 V vs. Li⁺/Li^(o) areadvantageously used as a component of negative electrodes inelectrochemical generators of primary and secondary type batteries orsupercapacitor. Similarly, compounds with redox couples comprisedbetween 2 and 3.7 V vs. Li⁺/Li^(o) are advantageously used as componentof positive electrodes in same devices or as an active or passiveelectrode in electrochromic devices.

[0026] The compounds of the present invention can be used alone or inmixtures thereof. They can also be used in conjunction with other redoxcompounds, in particular insertion compounds. Such insertion compoundsinclude, for negative electrodes, metallic lithium or alloys thereof,optionally in the form of a nanometric dispersion in lithium oxide;double nitrides of lithium and a metal of transition such as cobalt;oxides with a low potential of general formula Li_(1+y)Ti_(2−x/4)O₄O₄wherein x and y vary between 0 et 1; and carbon and carbonated productsresulting from the pyrolysis of organic matters. For the positiveelectrodes, the insertion compounds include oxides and sulfides oftransition metals, such as VO_(z) wherein z varies between 2 and 2.5;LiV₃O₈; Li_(a)N_(1−a)Co_(a)O₂ wherein a varies between 0 et 1; manganesespinels Li_(y)Mn_(2−x)M_(x)O₄ wherein x varies between 0 and 0.5 and yvaries between 0 and 2, and M is Li, Cr, Al, V, Ni; organicpolydisulfides; FeS; FeS₂; iron sulfate; iron and lithium phosphates andphosphosilicates of the olivine structure; or the substitution productof iron with manganese, either used alone or in mixtures.

[0027] The materials of the invention are particularly embodied incomposite electrodes containing the novel redox compounds, alone or inmixtures, at least one electronic conductor, and at least one polymericbinder. The electronic conductors are preferably selected fromcarbonated compounds such as carbon black, graphite powder, productsresulting from the pyrolysis of organic matters, in particular phenolicresins or polyacrylonitrile. When the electrode binder does not have anyelectrochemical function but only a mechanical function, the latter isadvantageously chosen from non-polar polymers likepolytetrafluoroethylene, co- or ter-polymer of ethylene, propylene and adiene, that allow the binding of the materials while leaving a porositysufficient to permit the required electrolyte penetration for properoperation of these redox materials.

[0028] Liquid electrolytes suitable with such type of redox materialsare those obtained by dissolving a salt or an acid in a solvent. Thesolvents are preferably chosen from cyclic or acyclic carbonates,γ-butyrolactone, monoalkylamides and di-alkylamides,tetraalkylsulfamides, dialkylated ethers of mono, di, tri andtetraethylene glycols, as well as oligomers having a mass lower than2000 g/mole, and their mixtures.

[0029] In a variation, the electrode binder has an ionic conductivityand allows the maintenance of an intimate contact between the particlesof the redox materials in the electrolyte while compensating, because oftheir plastic or elastomeric character, for the variations of volumeinherent to the operation of the electrode. In preferred embodiments,the electrolyte contains, individually or in a mixture, a polar-typepolymer, a polar solvent, and/or at least one ionic salt. The polar-typepolymers useful with the addition of a liquid solvent are preferablyselected from vinylidene fluoride-based homo- or copolymers,acrylonitrile-based homo- or copolymers, methyl methacrylate-based homo-or copolymers. The polar-type polymers useful with or without theaddition of a liquid solvent are preferably selected from polyetherssuch as ethylene oxide-based or propylene oxide-based homo- orcopolymers. In a variation of the preferred embodiment of the compoundsof the invention, ceramic or cross-linked particles are added to thepolymer electrolytes, to improve the mechanical properties.

[0030] Another interesting aspect of certain compounds of the inventionis their possibility to give, after oxidation beyond the normalreversible operating potential, an irreversible reaction liberatinglithium ions and gaseous compounds such as carbon monoxide or carbondioxide, nitrogen, ethylene or acetylene and their polymers. Theseproducts are eliminated from the generator medium (gas) or are inactive(polymers), and provide exceeding capacity that is useful to compensatefor the loss of capacity equilibrium between the anode and the cathode,caused mainly by the appearance of a passivation layer during the firstoperating cycles of the generator.

[0031] The following anions are illustrate compounds of the presentinvention, and should not be considered as limiting its scope.

[0032] The following examples are provided to illustrate preferredembodiments of the present invention, and should not be considered aslimiting its scope.

EXAMPLE 1

[0033] 2.10 g of dihydrated rhodizonic acid (Lancaster Windham) aretreated with 839 mg of monohydrate lithium hydroxide in isopropanol. Thesuspension is filtered and the black precipitate is dried under primaryvacuum at 50° C., to give the following lithium rhodizonate:

EXAMPLE 2

[0034] A lithium battery is fabricated with a film of lithium of athickness of 30 mm, a polymer electrolyte made of a complex of ethylenepolyoxide of a mass of 9×104 and lithiumbis-trifluoromethanesulfonylamide (LiTFSI) to obtain a ratio of thenumber of oxygens of the polymer on the lithium ions of 12:1. Thesolution in a common solvent is spread, evaporated and dried to form afilm of a thickness of about 80 μm. The positive electrode comprises amixture of 40% v/v of lithium rhodizonate as prepared in example 1, 5%by weight of carbon black (Ketjen black®) and 5% v/v of the electrolyteof the electrolytic composition previously described, but obtained witha polymer of a molecular weight of 10⁵. Acetonitrile is added to themixture, and the suspension obtained is homogenized by agitation withzircon balls in a stainless steel recipient for 24 h. The electrode isobtained by spreading the suspension on a stainless steel disk of 1.6 cmdiameter to form after evaporation of the solvent, a layer of athickness of 60 mm. The battery assembled in a neutral atmosphere(helium<1 ppm O₂, H₂O) in the form of a battery-button by pressing thethree components: anode-electrolyte-cathode and is tested at 80° C. inslow voltammetry with a digital potentiostat Macpile®. Two domains ofactivity corresponding each to a capacity of 305 mAh.g⁻¹ are apparent atabout 2.8 V and about 1.8 V with respect to the couple Li⁺/Li^(o). Forcomparison purposes, the capacity of a manganese spinal based electrodeLiMn₂O₄ possesses a theoretical maximum capacity of 153 mAh.g⁻¹ at 2.9 Vand modifications of this compound, in order to limit the dissolution ofthe manganese, such as the composition Li_(1.05)Mn_(1.85)Al_(0.1)O₄,have a capacity of 115 mAh.g⁻¹.

EXAMPLE 3

[0035] Tetrahydroxybenzoquinone is treated with an excess of lithiumisopropoxide in solution in isopropanol to give the lithium tetra-saltcorresponding to the following reaction:

C₆(O)₂(OH)₄+4 LiOCH(CH₃)₂ 43 C₆(O)₂(OLi)₄+4 HOCH(CH₃)₂

[0036] The black precipitate is filtered, dried and protected fromexposure to air.

[0037] A “rocking chair” or “lithium ion-type” battery is fabricated byproviding a graphite negative electrode (85% v/v) bonded with acopolymer of vinylidene fluoride and hexafluoropropene (PVDF), depositedon a thin sheet of copper (8 mm) and corresponding to a capacity of 3.1mAh.cm⁻² for the composition LiC₆. The positive electrode is a mixtureof carbon black of the Ketjen black type (7% v/v), lithium tetra-salt oftetrahydroxybenzoquinone (73% v/v) and PVDF (10%) deposited on analuminum collector of 10 mm. The capacity of the positive electrode fora reversible exchange of two electrons per molecule is 3.5 mAh.cm⁻². Theelectrolyte is made of a 1M solution of LiPF₆ in a mixture of ethylenecarbonate of 2-tertiobutoxyethyl-2′-methoxyethylether (50/50 v/v). Theliquid is immobilized in a porous membrane (Celgard®) of a thickness of25 mm. The battery is charged in an intentiostatic mode at 0.45 mAcm⁻²for 8 hours and the potential stabilizes at 3.6 V. The capacityextracted during discharge at C/5, i.e. 5 hours to extract the nominalcapacity, is of 3.8 mAh/cm², and stable during cycling for over 100cycles. The irreversible capacity of the first insertion of lithium inthe carbon, which is necessary to the formation of a passivation layer,is obtained by over-oxidation of the lithium salt according theequation:

Li₄C₆O₆→4Li⁺+4e ⁻+6 CO

[0038] The reversible operation of the battery takes place according tothe equation:

<Li₄C₆O₆>+2 <C₆>⇄<Li₂C₆O₆>+2 <LiC₆>

[0039] A generator identical to that of example 3 is fabricated bymixing two active compounds in the positive electrode, that is to say0.9 mg/cm² of the lithium tetra-salt of tetrahydroxybenzoquinone and 16mg/cm² of cobalt and lithium oxide LiCoO₂. The generator is charged at4.2 V and its cycling capacity is 2.5 mAh.cm⁻², which corresponds to 96%of the capacity of the cobalt oxide alone.

EXAMPLE 4

[0040] Potassium rhodizonate K₂C₆O₆ (Fluka) is treated to make anelectrochemical generator in the conditions similar to those of example2. The capacity is 210 mAh.g⁻¹, which is 93% of the theoreticalcapacity, which is 225 mAh.g⁻¹.

EXAMPLE 5

[0041] Copper rhodizonate is prepared by reacting 3.5 g of dihydratedrhodizonic acid with 3.5 g of dihydrated copper acetate in methanol.After evaporation of the solvent and the acetic acid produced by thereaction, copper rhodizonate is dried at 110° C. under primary vacuum.The capacity obtained in a generator comprising a lithium anode and agel-type electrolyte (45% copolymer of vinylidene fluoride andhexafluoropropene, 55% solution 1 M of LiBF₄ in γ-butyrolactone is of450 mAh.g⁻¹ and corresponds to 94% of the theoretical capacity for 4electrons between 3.3 et 2.5 V vs. Li⁺/Li^(o).

EXAMPLE 6

[0042] The compound

[0043] is obtained by reacting two equivalents of the lithium di-salt ofthe cyanamid Li₂NCN on tetrafluorobenzoquinone in DMF. The lithiumfluoride is separated by centrifugation and the blue lithium saltcorresponding to the above formula is precipitated in ether. Thiscompound possesses a capacity of 235 mAh.g⁻¹ at 2.6 V vs. Li⁺/Li^(o).

EXAMPLE 7

[0044] Rufigallic acid is prepared according to the method of Robiquet(Ann. 19, (1836), 204) by condensing gallic acid in concentratedsulfuric acid. The hexasubstituted lithium salt is prepared bysuspending rufigallic acid in THF under a neutral atmosphere andtreatment with lithium isopropoxide. The resulting salt is filtered anddried under dry nitrogen. Oxidation to the diquinonic form is performedby treating 4.0 g of this compound with a stoichiometric amount of[bis(trifluoroacetoxy)iodo]benzene (10.18 g) in acetonitrile. Afterfiltration and drying, the following compound is obtained:

[0045] This compound has a reversible capacity of 358 mAh.cm⁻² between2.5 and 3.2 V vs. Li⁺/Li^(o).

EXAMPLE 8

[0046] 1.40 g of trans-trans muconic acid (Sigma) are treated with 0.739g of lithium carbonate in methanol. After evaporation and vacuum drying,a generator similar to that of example 2 is fabricated by using acathodic mixture of 25% v/v of lithium muconate, 10% of Ketjen black and65% of polyelectrolyte. The compound has a reversible capacity of 0.8electron per formula at 1.3 V with respect to lithium. This compound canbe used as a negative electrode in lithium-ion type batteries.

EXAMPLE 9

[0047] A polymer possessing conjugated azino functions (diazo in areduced state) is prepared by action of 5 g of hydrazine monohydrateN₂H₄.H2O on the sodium salt of dihydroxytartric acid (22.6 g, JanssenChemicals) in acetic acid, under agitation for 24 hours. The dark brownpolymer is precipitated in isopropanol, separated by filtration anddried. The compound possesses redox properties of 2 electrons perrepetitive unit of the polymer, that is to say a capacity of 290mAh.g⁻¹. The lithium salt obtained by passage through an ion exchangecolumn has a capacity of 360 mAh.g⁻¹. The formula of the polymer reducedto 50% of its capacity is:

EXAMPLE 10

[0048] The potassium salt of dithiosquaric acid is prepared by reactingpotassium hydrogenosulfide (14.43 g, Alpha) ondibutoxy-3,4-cyclobutanel,2-dione (22.62 g Aldrich) in ethanol. A yellowsalt is obtained and recrystallized in a mixture water-ethanol, and isof formula:

[0049] To 18 g of this salt in suspension in acetonitrile are addedunder mechanical agitation a solution of tetrabutylammonium tribromide(34.6 g) in acetonitrile. After one hour, the yellow precipitate isfiltered and dried to give:

[0050] This compound possesses a reversible capacity of 385 mAh.g⁻¹ atan average potential of 2.8 V vs. Li⁺/Li^(o) and its solubility inelectrolytes like propylene carbonate and its mixtures or the polymerssolvating based on ethylene polyoxide is negligible, contrary topolydimercaptothiadiazole.

EXAMPLE 11

[0051] A Schiff polybase, poly(thiocyanic) acid, is prepared by reactingthiophosgene on thiourea in propylene carbonate in the presence ofpyridine. The dark brown suspension is poured in 100 ml of water and theprecipitate is filtered and washed with water. The product correspondsto the composition [C(SH)═N]_(n) with a developed formula:

[0052] The polymer in its reduced form is oxidized by iodine in solutionin acetonitrile in the presence of pyridine, and the suspensionremaining is washed with acetonitrile until a colorless eluate isobtained. The brown-black powder corresponds to the oxidation of thethiol groups to give the polymer:

[0053] An electrochemical generator similar to that of example 2 using apositive electrode containing 40% v/v of the compound thus obtainedshows a capacity of 360 mAh.g⁻¹ between 3 and 2.4 V vs. Li⁺/Li^(o), thatis to say 75% of the theoretical capacity which is 478 mAh.g⁻¹.

EXAMPLE 12

[0054] In the same manner as in example 11, the alternate copolymer offormula:

[0055] is prepared by replacing thiourea with the thioamide ofcyanoacetic acid. The polymer obtained after oxidation is a black powderhaving a capacity of 555 mAh.g⁻¹, with 50% between 3.2 V and 2.4 V vs.Li⁺/Li^(o).

EXAMPLE 13

[0056] Tetraaminobenzoquinone is prepared according to the method ofWallenfel & al. (Ann. 1963, 667). 16.8 g of this compound and 2.46 g ofchloranil (tetrachlorobenzoquinone) are mixed in a ball mill, and heatedunder argon at 250° C. in a Büchi TO51 oven followed by a treatment at350° C. under vacuum. The compound obtained corresponds to thepolyquinone-azine of formula:

[0057] The lithium salt of this compound is obtained by treating asuspension of the polymer with a solution of lithium isopropoxide inisopropanol. This compound has a reversible capacity of 345 Ah.g⁻¹between 2.4 and 3 V vs. Li⁺/Li^(o), that is to say 75% of thetheoretical capacity which is 420 mAh.g⁻¹. The lithium salt of thispolymer can also be obtained directly by reaction oftetrachlorobenzoquinone on lithium nitride in the molar ratio 1:2 bycogrinding in anhydrous DMF.

EXAMPLE 4

[0058] A polymer perfectly alternated between ethylene and carbonmonoxide is obtained according to the method of Hiraguri et al. (J. Am.Chem. Soc., 1987, 109, 3779). 56.06 g of this polymer are dissolved inhexafluoropropanol and treated with 10.39 g of lithium nitrite underreflux. The conjugated polymer appears under the form a blackprecipitate which is the lithium salt of formula:

EXAMPLE 15

[0059] Azino(bisacetique) acid is prepared by reacting hydrazine hydratein a stoichiometric amount with glyoxylic acid (Sigma) in isopropanol.The yellow-orange precipitate is dried and filtered, and the lithiumsalt is prepared in a solution methanol-water (50:50) by adding astoichiometric amount of lithium carbonate. The salt is dried undervacuum and tested in conditions similar to those of example 7. Thiscompound has a reversible redox activity at 1.7 V with respect tolithium.

EXAMPLE 16

[0060] A polymer of the polyamide type of formula:

[0061] is obtained by polycondensation of methyl oxalate with1,4-phenylene diamine in DMF. The reduced polymer is transformed in theoxidized quinoneimine form by reaction withbis[(trifluoroacetoxy)iodo]benzene in dichloromethane. The product hasthe developed formula:

[0062] It has a redox couple at 2.7 V vs. Li⁺/Li^(o) for a capacity of310 mAh.g⁻¹ (theoretical 347). Similar polymers are prepared by reactionof trifluoroethyl fumarate on 1,4-phenylene diamine (2.7 V vs.Li⁺/Li^(o)) or oxalyl chloride on 3,6-diamino pyridazine (2.9 V vs.Li⁺/Li^(o)).

EXAMPLE 17

[0063] A redox polymer is prepared by condensing fumaryl chloride onN,N′-dimethylhexamethylenediamine in solution in DMF, in the presence oftwo equivalents of pyridine. The polymer is precipitated in water andpurified by dissolution in acetone and reprecipitation in methanol. Thispolymer, mixed with carbon black, shows a redox activity at 1 V vs.Li⁺/Li^(o) for a capacity of 195 mAh.g⁻¹ (theoretical 247).

EXAMPLE 18

[0064] In the same manner as in Example 10, a redox polymer possessingan ionic conductivity and produced by the polycondensation ofoxalyl-diimidazole on 1,8-bis(methylamino)-3,6-dioxaoctane (Janssen) inDMF is prepared. This polymer also shows a redox activity at 1 V vs.Li⁺/Li^(o). At the neutral state, the polymer possesses complexingproperties towards salts and an ionic conductivity facilitating theredox reaction. The structure of this polymer in a partially reducedstate is

[0065] An amorphous copolymer can be obtained by using a mixture of thepreceding amine with 1,5-bis(methylamino)-3-oxapentane. In the samemanner, the oxalyl groups can be substituted with fumaryl or muconylgroups.

[0066] While the invention has been described in connection withspecific embodiments thereof, it will be understood that it is capableof further modifications, and this application is intended to cover anyvariations, uses or adaptations of the invention following, in general,the principles of the invention, and including such departures from thepresent description as come within known or customary practice withinthe art to which the invention pertains, and as may be applied to theessential features hereinbefore set forth, and as follows in the scopeof the appended claims.

What is claimed is:
 1. A redox compound having at least one state ofoxidation state represented by the general formula:

wherein M⁺ represents an alkaline metallic cation, an alkaline-earthcation, a transition metal cation, a rare earth cation, anorganometallic cation, an organic cation of the “nium” type, arepetitive unit of a cationic oxidized conjugated polymer, or amonomeric or polymeric cation optionally having a redox character; X isoxygen, NCN, or C(CN)₂; Z is C—Y or N; Y represents oxygen, sulfur, NCN,—C(CN)₂, with the proviso that when Y is sulfur and n is ≦4, then X isoxygen; R₁ is absent, O, S, NH, —(C═C)_(r)—, —(W═W)_(r)— wherein W isindependently CR⁶ or N; r varies between 1 and 12; and R⁶ is H, halogen,CN, or C₁₋₁₂ alkyl, C₂₋₁₂ alkenyl or C₆₋₁₄ aryl optionally having one ormore substituents oxa, aza or thia; and wherein 2 R⁶ groups can bebonded to form a cycle comprising from 3 to 7 members; R² and R³ are thesame or different and are absent, a carbonated divalent radical,optionally substituted with aza, oxa or thia; q varies between 0 et p; pvaries between 1 and 5; n varies between 1 and 10⁴; and wherein two ofR¹, R² and R³ can be bonded together to form a cycle comprising 3 to 7members.
 2. A compound according to claim 1 characterised in that it is:a rhodizonic acid salt; a rufigallic acid salt represented by theformula

and its oxidation compounds; an elagic acid salt represented by theformula

and its oxidation compounds, wherein the oxygen atoms with a double bondcan be replaced with a group NCN or C(CN)₂; a polymer of thiocyanic acidor 1-cyano-2-mercaptoacetylene represented by the formula

and its oxidation and reduction products, wherein Z═N or C—CN; a polymercontaining units derived from keto-pyridine represented by the formula

and its oxidation and reduction products; an alternated polymercontaining benzoquinone and pyrazine units and their oxidation andreduction products; a salt of 1,2-dimercaptocyclobutenedione(dithiosquarique) acid and its oxidation compounds, represented byformulae

and their products of oxidation; a salt of 1,5dihydropyrimido[5,4d]pyrimidine 2,4,6,8(3H, 7H)tetrone represented bythe formula

and its oxidation compounds: a salt of a dicarboxylic acid comprisinggroups linked with conjugated segments corresponding to the formula

wherein L is independently CR⁵, N or C—CN, and wherein R⁵ is hydrogen,C₁₋₁₂alkyl, C₂₋₁₂alkenyle, C₆₋₁₀aryl, C₆₋₁₀aryl C₁₋₁₂alkyl, C₁₋₁₂alkylC₆₋₁₀aryl optionally substituted with one or more oxa, aza or thia offrom 1 to 30 carbon atoms, and wherein 2 R⁵ can form an alphatic cycle,an aromatic cycle or a heterocycle containing from 4 to 8 carbon atomswhen both L are CR⁵; a polyamide derived from a dicarboxylic acidcomprising groups linked with conjugated segments, corresponding to theformula

wherein L et R⁵ are as defined above, and Q is a divalent alkylene,alkenylene, arylene, arylalkylene, alkylearylene of from 1 to 30 carbonatoms optionally containing oxa, aza or thia substituents.
 3. Compoundsaccording to claim 2, wherein the rhodizonic acid salt is lithiumrodizonate, potassium rhodizonate or copper rhodizonate, or theirreduction products.
 4. Compounds according to claim 1, characterized inthey are used as a negative electrode component in electrochemicalgenerators when redox couples are comprised between 0.1 and 2 V vs.Li⁺/Li^(o); or as a positive electrode component in electrochemicalgenerator or as an active or passive electrode in electrochromic deviceswhen redox couples are comprised between 2 et 3.7 V vs. Li⁺/Li^(o).
 5. Aredox electrode material characterized in that it contains, in whole orin part, a compound according to claim
 1. 6. A material according toclaim 5 characterized in that it furthers contains at least oneelectronic conductor and at least one binder.
 7. A material according toclaim 6 wherein the electronic conductor comprises carbon black orgraphite powder, and the binder comprises polytetrafluoroethylene, co-or ter-polymer of ethylene, propylene and a diene.
 8. A materialaccording to claim 5 characterized in that it can be used as a source oflithium to compensate for the inherent losses caused by the formation ofpassivation layers by the electrodes.
 9. A material according to claim 8characterized in that it comprises derivatives corresponding to thefollowing redox anions:


10. An electrical energy storage system of the primary or secondarygenerator-type or super-capacity, comprising an electrolyte, at leastone negative electrode and at least one positive electrode comprising acompound according to claim
 1. 11. A system according to claim 10wherein the alkaline cation is lithium cation.
 12. A system according toclaim 10 characterized in that the negative electrode is metalliclithium or an alloy thereof, optionally in the form of a nanometricdispersion in lithium oxide; double nitrides of lithium and a transitionmetal; low potential oxides of general formula Li_(1+y)Ti_(2−x/4)O₄wherein x and y vary between 0 et 1; carbon and carbonated productsobtained from the pyrolysis of organic materials.
 13. A system accordingto claim 10 wherein the positive electrode comprises a further electrodematerial compound selected from oxides and sulfides of transitionmetals.
 14. A system according to claim 10 wherein the electrolytecomprises a polar-type polymer, a polar solvent, or mixtures thereof,and at least one ionic salt.
 15. A system according to claim 14 whereinthe polar-type polymer is a polyether, a vinylidene fluoride-based homo-or copolymer, an acrylonitrile-based homo- or copolymer, or a methylmethacrylate-based homo- or copolymer.
 16. A system according to claim14 wherein the polar solvent comprises acyclic and cyclic carbonates,γ-butyrolactone, monoalkylamides and dialkylamides,tetraalkylsulfamides, dialkylatex ethers of mono-, di-, tri- ettetraethylene glycols and oligomers of weight inferiors to 2000 g/mole,and mixtures thereof.